Light Intensity-dependent Variation in Defect Contributions to Charge Transport and Recombination in a Planar MAPbI3 Perovskite Solar Cell

Abstract

We investigated operation of a planar MAPbI3 solar cell with respect to intensity variation ranging from 0.01 to 1 sun. Measured J-V curves consisted of space-charge-limited currents (SCLC) in a drift-dominant range and diode-like currents in a diffusion-dominant range. The variation of power-law exponent of SCLC showed that charge trapping by defects diminished as intensity increased, and that drift currents became eventually almost ohmic. Diode-like currents were analysed using a modified Shockley-equation model, the validity of which was confirmed by comparing measured and estimated open-circuit voltages. Intensity dependence of ideality factor led us to the conclusion that there were two other types of defects that contributed mostly as recombination centers. At low intensities, monomolecular recombination occurred due to one of these defects in addition to bimolecular recombination to result in the ideality factor of ~1.7. However, at high intensities, another type of defect not only took over monomolecular recombination, but also dominated bimolecular recombination to result in the ideality factor of ~2.0. These ideality-factor values were consistent with those representing the intensity dependence of loss-current ratio estimated by using a constant internal-quantum-efficiency approximation. The presence of multiple types of defects was corroborated by findings from equivalent-circuit analysis of impedance spectra.

Polariton-assisted excitation energy channeling in organic heterojunctions

“…However, as shown in Fig. 4d , the photocurrent ( J ph ) with increased illumination intensity ( P ) in both devices follow , where α is regarded as a measure of the efficiency of free charge extraction of the system 48 , 49 . The value of α obtained from the cavity and reference devices is similar, indicating that the change of anode material does not significantly affect in the two systems.…”

Polariton-Assisted Excitation Energy Channeling in Organic Heterojunctions

“…However, as shown in Figure 4d, the photocurrent (J ph ) with increased illumination intensity (P) in both devices follow ∝ , where α is regarded as a measure of the efficiency of free charge extraction ( ) of the system. 43,44 The value of α obtained from the cavity and reference devices are similar, indicating that the change of anode material does not significantly affect in the two systems. Thus, the enhanced photon-to-current efficiency in the cavity device can be attributed to the increased efficiency of exciton harvesting to interfacial charge transfer states ( ) in the strong coupling regime.…”

Surface-Passivated CsPbBr3 for Developing Efficient and Stable Perovskite Photovoltaics

“…The low differences (<10%) between JSC from J-V curve and EQE indicate that our photovoltaic measurements are done without critical error [27]. The enhanced performances of PPVs after introducing OABr surface treatment were further explored by measuring the light intensity-dependent photovoltaic parameters, as shown in Figure 2c [28]. The ideality (n) and the power factor (α) of PPVs were extracted using the below equations.…”